1. Field of the Invention
The present invention relates to a device which will permit applying the necessary loads for testing front wheel drive and steering units for vehicles, and similar devices that require "jounce" input as well as torque and axial loading.
2. Description of the Prior Art
Four square test arrangements have been used for axle testing, utilizing hydraulic actuators for providing torque loads in the past. A typical four square test stand with torque stabilization is shown in U.S. Pat. No. 3,690,168 issued Sept. 12, 1972 to Petersen, and assigned to the same assignee as this application. The teaching of advantages of four square testing and the ability to control the torque in axles being tested in set forth in such patent. Also, the use of hydraulic commutators to provide fluid under pressure to the actuators loading the axles in torque is disclosed.
A type of jounce actuator is shown in U.S. Pat. No. 3,796,092 which issued Mar. 12, 1974 to Klinger et al. A torsion test stand has a center section 11 in this patent which can be moved by a cylinder 17 and the section 11 holds the test specimen between two universal joints. The disclosure is quite schematic, but it does indicate the ability to offset the center section or test section, and the cylinder permits at least some movement of the specimens laterally to their axes.
U.S. Pat. No. 4,089,211 shows an elastomeric bearing test machine which permits loading in several axes. This machine is not a four square setup designed for testing axles and applying jouncing loads.
U.S. Pat. No. 3,713,330 shows means for applying loads along different axes in a test setup, as does U.S. Pat. No. 3,696,663. Other patents which are believed to represent the state of the art include the following:
______________________________________ U.S. Pat. No. Inventor ______________________________________ 926,513 Souther 1,479,338 Thomas 2,157,903 Lapsley 2,316,253 Keinath 2,371,607 Collins 3,195,350 Reed 3,605,488 Foster 3,696,663 Klinger 3,729,632 Miller 4,263,809 Petersen et al ______________________________________